docs: def _process_organism_dbxref(self, limit):
          """
          This is the mapping between the flybase organisms and
          external identifier "FBsp". We will want to use the NCBITaxon as
          the primary, if possible, but will default to a blank node/internal id
          if that is all that is available
          But we need to make the equivalences/sameAs.
  
          :param limit:
          :return:
  
          """
          if self.test_mode:
              graph = self.testgraph
          else:
              graph = self.graph
          model = Model(graph)
          line_counter = 0
          raw = '/'.join((self.rawdir, 'organism_dbxref'))
          LOG.info("processing organsim dbxref mappings")
          with open(raw, 'r') as f:
              f.readline()  # read the header row; skip
              filereader = csv.reader(f, delimiter='\t', quotechar='\"')
              for line in filereader:
  
                  (organism_dbxref_id, organism_id, dbxref_id, is_current) = line
  
                  if self.test_mode \
                          and int(organism_id) not in self.test_keys['organism']:
                      continue
  
                  organism_key = organism_id
                  if organism_key not in self.idhash['organism']:
                      continue
                  organism_id = self.idhash['organism'][organism_key]
  
                  dbxref_key = dbxref_id
                  dbxrefs = self.dbxrefs.get(dbxref_key)
                  if dbxrefs is not None:
                      for d in dbxrefs:
                          did = dbxrefs.get(d)
                          # don't make something sameAs itself
                          if did == organism_id:
                              continue
                          dlabel = self.label_hash.get(did)
                          model.addXref(organism_id, did)
                          if re.match(r'NCBITaxon', did):
                              model.makeLeader(did)
                          else:
                              model.addIndividualToGraph(did, dlabel)
                          line_counter += 1
  
                  if not self.test_mode and limit is not None and line_counter > limit:
                      break
  
          return